diff --git a/tests/ui/methods.rs b/tests/ui/methods.rs
index a422cffafab..20776ca15da 100644
--- a/tests/ui/methods.rs
+++ b/tests/ui/methods.rs
@@ -189,15 +189,6 @@ impl IteratorFalsePositives {
}
}
-#[derive(Copy, Clone)]
-struct HasChars;
-
-impl HasChars {
- fn chars(self) -> std::str::Chars<'static> {
- "HasChars".chars()
- }
-}
-
/// Checks implementation of `FILTER_NEXT` lint
fn filter_next() {
let v = vec![3, 2, 1, 0, -1, -2, -3];
@@ -431,25 +422,3 @@ struct MyError(()); // doesn't implement Debug
struct MyErrorWithParam<T> {
x: T
}
-
-fn str_extend_chars() {
- let abc = "abc";
- let def = String::from("def");
- let mut s = String::new();
-
- s.push_str(abc);
- s.extend(abc.chars());
-
- s.push_str("abc");
- s.extend("abc".chars());
-
- s.push_str(&def);
- s.extend(def.chars());
-
- s.extend(abc.chars().skip(1));
- s.extend("abc".chars().skip(1));
- s.extend(['a', 'b', 'c'].iter());
-
- let f = HasChars;
- s.extend(f.chars());
-}
diff --git a/tests/ui/methods.stderr b/tests/ui/methods.stderr
index d80ff30ec71..1b5deef998e 100644
--- a/tests/ui/methods.stderr
+++ b/tests/ui/methods.stderr
@@ -214,356 +214,336 @@ error: unnecessary structure name repetition
| ^^^^^^^^^^^^^^^^^^^^^^ help: use the applicable keyword: `Self`
error: called `filter(p).next()` on an `Iterator`. This is more succinctly expressed by calling `.find(p)` instead.
- --> $DIR/methods.rs:206:13
+ --> $DIR/methods.rs:197:13
|
-206 | let _ = v.iter().filter(|&x| *x < 0).next();
+197 | let _ = v.iter().filter(|&x| *x < 0).next();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: `-D filter-next` implied by `-D warnings`
= note: replace `filter(|&x| *x < 0).next()` with `find(|&x| *x < 0)`
error: called `filter(p).next()` on an `Iterator`. This is more succinctly expressed by calling `.find(p)` instead.
- --> $DIR/methods.rs:209:13
+ --> $DIR/methods.rs:200:13
|
-209 | let _ = v.iter().filter(|&x| {
+200 | let _ = v.iter().filter(|&x| {
| _____________^
-210 | | *x < 0
-211 | | }
-212 | | ).next();
+201 | | *x < 0
+202 | | }
+203 | | ).next();
| |___________________________^
error: called `is_some()` after searching an `Iterator` with find. This is more succinctly expressed by calling `any()`.
- --> $DIR/methods.rs:224:13
+ --> $DIR/methods.rs:215:13
|
-224 | let _ = v.iter().find(|&x| *x < 0).is_some();
+215 | let _ = v.iter().find(|&x| *x < 0).is_some();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: `-D search-is-some` implied by `-D warnings`
= note: replace `find(|&x| *x < 0).is_some()` with `any(|&x| *x < 0)`
error: called `is_some()` after searching an `Iterator` with find. This is more succinctly expressed by calling `any()`.
- --> $DIR/methods.rs:227:13
+ --> $DIR/methods.rs:218:13
|
-227 | let _ = v.iter().find(|&x| {
+218 | let _ = v.iter().find(|&x| {
| _____________^
-228 | | *x < 0
-229 | | }
-230 | | ).is_some();
+219 | | *x < 0
+220 | | }
+221 | | ).is_some();
| |______________________________^
error: called `is_some()` after searching an `Iterator` with position. This is more succinctly expressed by calling `any()`.
- --> $DIR/methods.rs:233:13
+ --> $DIR/methods.rs:224:13
|
-233 | let _ = v.iter().position(|&x| x < 0).is_some();
+224 | let _ = v.iter().position(|&x| x < 0).is_some();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: replace `position(|&x| x < 0).is_some()` with `any(|&x| x < 0)`
error: called `is_some()` after searching an `Iterator` with position. This is more succinctly expressed by calling `any()`.
- --> $DIR/methods.rs:236:13
+ --> $DIR/methods.rs:227:13
|
-236 | let _ = v.iter().position(|&x| {
+227 | let _ = v.iter().position(|&x| {
| _____________^
-237 | | x < 0
-238 | | }
-239 | | ).is_some();
+228 | | x < 0
+229 | | }
+230 | | ).is_some();
| |______________________________^
error: called `is_some()` after searching an `Iterator` with rposition. This is more succinctly expressed by calling `any()`.
- --> $DIR/methods.rs:242:13
+ --> $DIR/methods.rs:233:13
|
-242 | let _ = v.iter().rposition(|&x| x < 0).is_some();
+233 | let _ = v.iter().rposition(|&x| x < 0).is_some();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: replace `rposition(|&x| x < 0).is_some()` with `any(|&x| x < 0)`
error: called `is_some()` after searching an `Iterator` with rposition. This is more succinctly expressed by calling `any()`.
- --> $DIR/methods.rs:245:13
+ --> $DIR/methods.rs:236:13
|
-245 | let _ = v.iter().rposition(|&x| {
+236 | let _ = v.iter().rposition(|&x| {
| _____________^
-246 | | x < 0
-247 | | }
-248 | | ).is_some();
+237 | | x < 0
+238 | | }
+239 | | ).is_some();
| |______________________________^
error: unnecessary structure name repetition
- --> $DIR/methods.rs:262:21
+ --> $DIR/methods.rs:253:21
|
-262 | fn new() -> Foo { Foo }
+253 | fn new() -> Foo { Foo }
| ^^^ help: use the applicable keyword: `Self`
error: use of `unwrap_or` followed by a function call
- --> $DIR/methods.rs:280:5
+ --> $DIR/methods.rs:271:5
|
-280 | with_constructor.unwrap_or(make());
+271 | with_constructor.unwrap_or(make());
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `with_constructor.unwrap_or_else(make)`
|
= note: `-D or-fun-call` implied by `-D warnings`
error: use of `unwrap_or` followed by a call to `new`
- --> $DIR/methods.rs:283:5
+ --> $DIR/methods.rs:274:5
|
-283 | with_new.unwrap_or(Vec::new());
+274 | with_new.unwrap_or(Vec::new());
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `with_new.unwrap_or_default()`
error: use of `unwrap_or` followed by a function call
- --> $DIR/methods.rs:286:5
+ --> $DIR/methods.rs:277:5
|
-286 | with_const_args.unwrap_or(Vec::with_capacity(12));
+277 | with_const_args.unwrap_or(Vec::with_capacity(12));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `with_const_args.unwrap_or_else(|| Vec::with_capacity(12))`
error: use of `unwrap_or` followed by a function call
+ --> $DIR/methods.rs:280:5
+ |
+280 | with_err.unwrap_or(make());
+ | ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `with_err.unwrap_or_else(|_| make())`
+
+error: use of `unwrap_or` followed by a function call
+ --> $DIR/methods.rs:283:5
+ |
+283 | with_err_args.unwrap_or(Vec::with_capacity(12));
+ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `with_err_args.unwrap_or_else(|_| Vec::with_capacity(12))`
+
+error: use of `unwrap_or` followed by a call to `default`
+ --> $DIR/methods.rs:286:5
+ |
+286 | with_default_trait.unwrap_or(Default::default());
+ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `with_default_trait.unwrap_or_default()`
+
+error: use of `unwrap_or` followed by a call to `default`
--> $DIR/methods.rs:289:5
|
-289 | with_err.unwrap_or(make());
- | ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `with_err.unwrap_or_else(|_| make())`
+289 | with_default_type.unwrap_or(u64::default());
+ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `with_default_type.unwrap_or_default()`
error: use of `unwrap_or` followed by a function call
--> $DIR/methods.rs:292:5
|
-292 | with_err_args.unwrap_or(Vec::with_capacity(12));
- | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `with_err_args.unwrap_or_else(|_| Vec::with_capacity(12))`
-
-error: use of `unwrap_or` followed by a call to `default`
- --> $DIR/methods.rs:295:5
- |
-295 | with_default_trait.unwrap_or(Default::default());
- | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `with_default_trait.unwrap_or_default()`
-
-error: use of `unwrap_or` followed by a call to `default`
- --> $DIR/methods.rs:298:5
- |
-298 | with_default_type.unwrap_or(u64::default());
- | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `with_default_type.unwrap_or_default()`
-
-error: use of `unwrap_or` followed by a function call
- --> $DIR/methods.rs:301:5
- |
-301 | with_vec.unwrap_or(vec![]);
+292 | with_vec.unwrap_or(vec![]);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `with_vec.unwrap_or_else(|| < [ _ ] > :: into_vec ( box [ $ ( $ x ) , * ] ))`
error: use of `unwrap_or` followed by a function call
- --> $DIR/methods.rs:306:5
+ --> $DIR/methods.rs:297:5
|
-306 | without_default.unwrap_or(Foo::new());
+297 | without_default.unwrap_or(Foo::new());
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `without_default.unwrap_or_else(Foo::new)`
error: use of `or_insert` followed by a function call
- --> $DIR/methods.rs:309:5
+ --> $DIR/methods.rs:300:5
|
-309 | map.entry(42).or_insert(String::new());
+300 | map.entry(42).or_insert(String::new());
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `map.entry(42).or_insert_with(String::new)`
error: use of `or_insert` followed by a function call
- --> $DIR/methods.rs:312:5
+ --> $DIR/methods.rs:303:5
|
-312 | btree.entry(42).or_insert(String::new());
+303 | btree.entry(42).or_insert(String::new());
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `btree.entry(42).or_insert_with(String::new)`
error: use of `unwrap_or` followed by a function call
- --> $DIR/methods.rs:315:13
+ --> $DIR/methods.rs:306:13
|
-315 | let _ = stringy.unwrap_or("".to_owned());
+306 | let _ = stringy.unwrap_or("".to_owned());
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `stringy.unwrap_or_else(|| "".to_owned())`
error: called `.iter().nth()` on a Vec. Calling `.get()` is both faster and more readable
- --> $DIR/methods.rs:326:23
+ --> $DIR/methods.rs:317:23
|
-326 | let bad_vec = some_vec.iter().nth(3);
+317 | let bad_vec = some_vec.iter().nth(3);
| ^^^^^^^^^^^^^^^^^^^^^^
|
= note: `-D iter-nth` implied by `-D warnings`
error: called `.iter().nth()` on a slice. Calling `.get()` is both faster and more readable
- --> $DIR/methods.rs:327:26
+ --> $DIR/methods.rs:318:26
|
-327 | let bad_slice = &some_vec[..].iter().nth(3);
+318 | let bad_slice = &some_vec[..].iter().nth(3);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^
error: called `.iter().nth()` on a slice. Calling `.get()` is both faster and more readable
- --> $DIR/methods.rs:328:31
+ --> $DIR/methods.rs:319:31
|
-328 | let bad_boxed_slice = boxed_slice.iter().nth(3);
+319 | let bad_boxed_slice = boxed_slice.iter().nth(3);
| ^^^^^^^^^^^^^^^^^^^^^^^^^
error: called `.iter().nth()` on a VecDeque. Calling `.get()` is both faster and more readable
- --> $DIR/methods.rs:329:29
+ --> $DIR/methods.rs:320:29
|
-329 | let bad_vec_deque = some_vec_deque.iter().nth(3);
+320 | let bad_vec_deque = some_vec_deque.iter().nth(3);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: called `.iter_mut().nth()` on a Vec. Calling `.get_mut()` is both faster and more readable
- --> $DIR/methods.rs:334:23
+ --> $DIR/methods.rs:325:23
|
-334 | let bad_vec = some_vec.iter_mut().nth(3);
+325 | let bad_vec = some_vec.iter_mut().nth(3);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^
error: called `.iter_mut().nth()` on a slice. Calling `.get_mut()` is both faster and more readable
- --> $DIR/methods.rs:337:26
+ --> $DIR/methods.rs:328:26
|
-337 | let bad_slice = &some_vec[..].iter_mut().nth(3);
+328 | let bad_slice = &some_vec[..].iter_mut().nth(3);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: called `.iter_mut().nth()` on a VecDeque. Calling `.get_mut()` is both faster and more readable
- --> $DIR/methods.rs:340:29
+ --> $DIR/methods.rs:331:29
|
-340 | let bad_vec_deque = some_vec_deque.iter_mut().nth(3);
+331 | let bad_vec_deque = some_vec_deque.iter_mut().nth(3);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: called `skip(x).next()` on an iterator. This is more succinctly expressed by calling `nth(x)`
- --> $DIR/methods.rs:352:13
+ --> $DIR/methods.rs:343:13
|
-352 | let _ = some_vec.iter().skip(42).next();
+343 | let _ = some_vec.iter().skip(42).next();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: `-D iter-skip-next` implied by `-D warnings`
error: called `skip(x).next()` on an iterator. This is more succinctly expressed by calling `nth(x)`
- --> $DIR/methods.rs:353:13
+ --> $DIR/methods.rs:344:13
|
-353 | let _ = some_vec.iter().cycle().skip(42).next();
+344 | let _ = some_vec.iter().cycle().skip(42).next();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: called `skip(x).next()` on an iterator. This is more succinctly expressed by calling `nth(x)`
- --> $DIR/methods.rs:354:13
+ --> $DIR/methods.rs:345:13
|
-354 | let _ = (1..10).skip(10).next();
+345 | let _ = (1..10).skip(10).next();
| ^^^^^^^^^^^^^^^^^^^^^^^
error: called `skip(x).next()` on an iterator. This is more succinctly expressed by calling `nth(x)`
- --> $DIR/methods.rs:355:14
+ --> $DIR/methods.rs:346:14
|
-355 | let _ = &some_vec[..].iter().skip(3).next();
+346 | let _ = &some_vec[..].iter().skip(3).next();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: called `.get().unwrap()` on a slice. Using `[]` is more clear and more concise
- --> $DIR/methods.rs:381:17
+ --> $DIR/methods.rs:372:17
|
-381 | let _ = boxed_slice.get(1).unwrap();
+372 | let _ = boxed_slice.get(1).unwrap();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `&boxed_slice[1]`
|
= note: `-D get-unwrap` implied by `-D warnings`
error: called `.get().unwrap()` on a slice. Using `[]` is more clear and more concise
- --> $DIR/methods.rs:382:17
+ --> $DIR/methods.rs:373:17
|
-382 | let _ = some_slice.get(0).unwrap();
+373 | let _ = some_slice.get(0).unwrap();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `&some_slice[0]`
error: called `.get().unwrap()` on a Vec. Using `[]` is more clear and more concise
- --> $DIR/methods.rs:383:17
+ --> $DIR/methods.rs:374:17
|
-383 | let _ = some_vec.get(0).unwrap();
+374 | let _ = some_vec.get(0).unwrap();
| ^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `&some_vec[0]`
error: called `.get().unwrap()` on a VecDeque. Using `[]` is more clear and more concise
- --> $DIR/methods.rs:384:17
+ --> $DIR/methods.rs:375:17
|
-384 | let _ = some_vecdeque.get(0).unwrap();
+375 | let _ = some_vecdeque.get(0).unwrap();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `&some_vecdeque[0]`
error: called `.get().unwrap()` on a HashMap. Using `[]` is more clear and more concise
- --> $DIR/methods.rs:385:17
+ --> $DIR/methods.rs:376:17
|
-385 | let _ = some_hashmap.get(&1).unwrap();
+376 | let _ = some_hashmap.get(&1).unwrap();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `&some_hashmap[&1]`
error: called `.get().unwrap()` on a BTreeMap. Using `[]` is more clear and more concise
- --> $DIR/methods.rs:386:17
+ --> $DIR/methods.rs:377:17
|
-386 | let _ = some_btreemap.get(&1).unwrap();
+377 | let _ = some_btreemap.get(&1).unwrap();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `&some_btreemap[&1]`
error: called `.get_mut().unwrap()` on a slice. Using `[]` is more clear and more concise
- --> $DIR/methods.rs:391:10
+ --> $DIR/methods.rs:382:10
|
-391 | *boxed_slice.get_mut(0).unwrap() = 1;
+382 | *boxed_slice.get_mut(0).unwrap() = 1;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `&mut boxed_slice[0]`
error: called `.get_mut().unwrap()` on a slice. Using `[]` is more clear and more concise
- --> $DIR/methods.rs:392:10
+ --> $DIR/methods.rs:383:10
|
-392 | *some_slice.get_mut(0).unwrap() = 1;
+383 | *some_slice.get_mut(0).unwrap() = 1;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `&mut some_slice[0]`
error: called `.get_mut().unwrap()` on a Vec. Using `[]` is more clear and more concise
- --> $DIR/methods.rs:393:10
+ --> $DIR/methods.rs:384:10
|
-393 | *some_vec.get_mut(0).unwrap() = 1;
+384 | *some_vec.get_mut(0).unwrap() = 1;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `&mut some_vec[0]`
error: called `.get_mut().unwrap()` on a VecDeque. Using `[]` is more clear and more concise
- --> $DIR/methods.rs:394:10
+ --> $DIR/methods.rs:385:10
|
-394 | *some_vecdeque.get_mut(0).unwrap() = 1;
+385 | *some_vecdeque.get_mut(0).unwrap() = 1;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `&mut some_vecdeque[0]`
error: used unwrap() on an Option value. If you don't want to handle the None case gracefully, consider using expect() to provide a better panic message
- --> $DIR/methods.rs:408:13
+ --> $DIR/methods.rs:399:13
|
-408 | let _ = opt.unwrap();
+399 | let _ = opt.unwrap();
| ^^^^^^^^^^^^
|
= note: `-D option-unwrap-used` implied by `-D warnings`
error: used unwrap() on a Result value. If you don't want to handle the Err case gracefully, consider using expect() to provide a better panic message
- --> $DIR/methods.rs:411:13
+ --> $DIR/methods.rs:402:13
|
-411 | let _ = res.unwrap();
+402 | let _ = res.unwrap();
| ^^^^^^^^^^^^
|
= note: `-D result-unwrap-used` implied by `-D warnings`
error: called `ok().expect()` on a Result value. You can call `expect` directly on the `Result`
- --> $DIR/methods.rs:413:5
+ --> $DIR/methods.rs:404:5
|
-413 | res.ok().expect("disaster!");
+404 | res.ok().expect("disaster!");
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: `-D ok-expect` implied by `-D warnings`
error: called `ok().expect()` on a Result value. You can call `expect` directly on the `Result`
- --> $DIR/methods.rs:419:5
+ --> $DIR/methods.rs:410:5
|
-419 | res3.ok().expect("whoof");
+410 | res3.ok().expect("whoof");
| ^^^^^^^^^^^^^^^^^^^^^^^^^
error: called `ok().expect()` on a Result value. You can call `expect` directly on the `Result`
- --> $DIR/methods.rs:421:5
+ --> $DIR/methods.rs:412:5
|
-421 | res4.ok().expect("argh");
+412 | res4.ok().expect("argh");
| ^^^^^^^^^^^^^^^^^^^^^^^^
error: called `ok().expect()` on a Result value. You can call `expect` directly on the `Result`
- --> $DIR/methods.rs:423:5
+ --> $DIR/methods.rs:414:5
|
-423 | res5.ok().expect("oops");
+414 | res5.ok().expect("oops");
| ^^^^^^^^^^^^^^^^^^^^^^^^
error: called `ok().expect()` on a Result value. You can call `expect` directly on the `Result`
- --> $DIR/methods.rs:425:5
+ --> $DIR/methods.rs:416:5
|
-425 | res6.ok().expect("meh");
+416 | res6.ok().expect("meh");
| ^^^^^^^^^^^^^^^^^^^^^^^
-error: calling `.extend(_.chars())`
- --> $DIR/methods.rs:441:5
- |
-441 | s.extend(abc.chars());
- | ^^^^^^^^^^^^^^^^^^^^^ help: try this: `s.push_str(abc)`
- |
- = note: `-D string-extend-chars` implied by `-D warnings`
-
-error: calling `.extend(_.chars())`
- --> $DIR/methods.rs:444:5
- |
-444 | s.extend("abc".chars());
- | ^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `s.push_str("abc")`
-
-error: calling `.extend(_.chars())`
- --> $DIR/methods.rs:447:5
- |
-447 | s.extend(def.chars());
- | ^^^^^^^^^^^^^^^^^^^^^ help: try this: `s.push_str(&def)`
-
diff --git a/tests/ui/string_extend.rs b/tests/ui/string_extend.rs
new file mode 100644
index 00000000000..d99adb19f89
--- /dev/null
+++ b/tests/ui/string_extend.rs
@@ -0,0 +1,30 @@
+#[derive(Copy, Clone)]
+struct HasChars;
+
+impl HasChars {
+ fn chars(self) -> std::str::Chars<'static> {
+ "HasChars".chars()
+ }
+}
+
+fn main() {
+ let abc = "abc";
+ let def = String::from("def");
+ let mut s = String::new();
+
+ s.push_str(abc);
+ s.extend(abc.chars());
+
+ s.push_str("abc");
+ s.extend("abc".chars());
+
+ s.push_str(&def);
+ s.extend(def.chars());
+
+ s.extend(abc.chars().skip(1));
+ s.extend("abc".chars().skip(1));
+ s.extend(['a', 'b', 'c'].iter());
+
+ let f = HasChars;
+ s.extend(f.chars());
+}
diff --git a/tests/ui/string_extend.stderr b/tests/ui/string_extend.stderr
new file mode 100644
index 00000000000..1f6d9400743
--- /dev/null
+++ b/tests/ui/string_extend.stderr
@@ -0,0 +1,20 @@
+error: calling `.extend(_.chars())`
+ --> $DIR/string_extend.rs:16:5
+ |
+16 | s.extend(abc.chars());
+ | ^^^^^^^^^^^^^^^^^^^^^ help: try this: `s.push_str(abc)`
+ |
+ = note: `-D string-extend-chars` implied by `-D warnings`
+
+error: calling `.extend(_.chars())`
+ --> $DIR/string_extend.rs:19:5
+ |
+19 | s.extend("abc".chars());
+ | ^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `s.push_str("abc")`
+
+error: calling `.extend(_.chars())`
+ --> $DIR/string_extend.rs:22:5
+ |
+22 | s.extend(def.chars());
+ | ^^^^^^^^^^^^^^^^^^^^^ help: try this: `s.push_str(&def)`
+